Overcoming solar panels’ winter blahs

Not every green technology works the same way in every place.

Snow would seem to be at odds with solar panels, because it can cover them up. But if the panels are kept clean, a bright snow-white environment increases output.

Published on Fri Mar 04 2011

Not every green technology works the same way in every place.

Electric-car manufacturers have to take into account the impact of cold weather on battery performance before selling into northern markets. Developers of wind farms have to be aware of the potential of ice build-up on turbine blades and how this might affect maintenance costs.

Cold and ice and snow aren’t deal-breakers, but Ontario isn’t California and this must be factored into all purchase decisions and designs. Each jurisdiction brings its own set of challenges that need to be managed.

A research project taking place at St. Lawrence College and Queen’s University in Kingston is studying the complex relationship between snow and solar PV panels. It’s certainly something worth knowing. There are more than 25,000 solar projects — from small rooftop systems to large, sprawling “farms” — expected to be developed in the province over the coming two years as part of the renewable energy feed-in-tariff program.

According to the researchers, and to my surprise, nearly three-quarters of all solar PV panels installed globally in 2009 were in countries that experience some snowfall. This reflects solar subsidy programs in places such as Germany, Japan, the Czech Republic and, of course, Ontario.

A preliminary Queen’s study of how snow affects panel performance has already revealed some interesting data. “Snow effect increases albedo, which had a significant (positive) effect on the performance of panels,” explained Adegboyega Babasola, lead researcher at St. Lawrence College’s Sustainable Energy Applied Research Centre.

Albedo is the reflective power of a surface. We know snow reflects light. We know dark pavement absorbs it, which is why it gets so hot in the summer. “While snow on the panels reduced their power output, snow on the ground increased albedo, and thus increased solar irradiation onto the panels,” said Babasola, adding that measurements varied by panel angle and style.

In other words, it’s sometimes a good thing if there is a lot of snow on the ground surrounding a solar panel, because it means the panel is hit with more light and can potentially produce more electricity. Assuming, of course, the panel isn’t covered in snow.

The preliminary study took place at a small test site in Kingston. Only 16 panels were monitored, each installed at different angles ranging from zero to 70 degrees, so the scope of the study was limited.

The research team, led by Queen’s engineering professor Joshua Pearce, is expanding on those finding with a much larger follow-up study that will gather data from four sites — Queen’s, the Kortright Centre in Woodbridge, and two sites at St. Lawrence College, part of a new outdoor test facility that is one of the most advanced in North America.

Partners in the project include Natural Resources Canada, chemical giant DuPont Canada, and several companies from the solar sector.

“There have been very few comprehensive studies performed which attempt to quantify the effects of snowfall, and none which provide universally applicable estimations of snow-related losses,” said Babasola.

“The first goal of the snow study is to attempt to gain a better understanding of the effects, and to provide some recommendations for reducing these losses.”

Not every solar panel is created equal. Thin-film panels, for example, can produce electricity from diffuse light, while conventional crystalline solar panels need direct light. Thin-film panels may benefit much more from the albedo effect, so could prove a better option for areas that get more snowfall.

What is the ideal angle of placement for a panel to get maximum exposure to sunlight, but also to make sure the snow can slide off easily during and after a snowfall? Does the loss of performance from snow cover, and therefore the reduction in revenues from power sold into the grid, make it worthwhile to invest in snow removal? And what is the most effective, lowest-cost removal option?

How much does the albedo effect compensate for the reduction in performance from snow cover? Can special, slippery coatings be used to speed up snow shedding?

These are just some of the questions the researchers hope to answer, which is good for Ontario, because you can bet solar manufacturers in China and California aren’t going to answer them for us.

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